Question

Focal length of convex lens is 3cm. Find the image distance if object of height 2cm is placed at 7cm from lens?

Answer 1

The image will be formed `5.25cm` behind the lens.

Explanation:

Using the lens formula:

`1/f =1/v -1/u` {where `u= -7, f= 3cm`}

`1/f +1/u =1/v`

`1/3 -1/7 =1/v`

`4/21= 1/v`

`v= 21/4 =5.25cm.`